Freddie Mac, the mortgage finance group, yesterday reported a record loss of $2.45 billion (£1.23 billion) for its fourth quarter as it suffered from a surge in defaults on US home loans.

Like its key rival, Fannie Mae, Freddie Mac makes most of its money from buying home loans from the mortgage lenders, packaging them into securities and selling them on.

It guarantees the interest and principal payments in the event of a default on the underlying assets and charges a fee for this service.

The group also holds on to some of the bonds on its balance sheet as an investment.

But both Fannie Mae and Freddie Mac have been badly hit by the housing crisis, which has left them facing huge payouts on the bonds that they guarantee, as well as massive losses on the securities they own.

Richard Syron, Freddie Mac's chief executive, said: “Today's economy represents one of the most severe housing downturns in American history.

“We remain extremely cautious as we enter 2008. If the economy weakens substantially from here, a possibility for which we need to be prepared, it will have a further negative effect on homeowners across the country and drive credit costs higher.”

Freddie Mac sold $6 billion of stock during the fourth quarter and cut its dividend in half in an attempt to bolster its capital reserves.

Freddie Mac's loss, which follows a $401 million loss the year before, was announced one day after Fannie Mae revealed a $3.55 billion fourth-quarter loss.

The two so-called secondary mortgage groups own, or guarantee, about 45 per cent of the $11,500 billion US home loan market between them, making them a vital source of mortgage financing in America.

Separately, Thornburg Mortgage, the US lender, said it had been forced to meet $300 million of margin calls in the past two weeks as nervous creditors look to safeguard their loans.

The margin calls relate to mortgage-backed securities that Thornburg owns — rather than home loans it has made — which the group said had lost between 10 per cent and 15percent of their value this month.

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